Hi,

The fix for #1014 (#1015) introduced a new requirement for various constructs (FixedSized, NullTerminated, etc.) that the underlying stream now has to be tellable. I don't use Tell, so the breakage was a little surprising to me when I updated from 2.10.69. (I understand that some construct implementations require seekable/tellable behavior, but I didn't think all of them did.)

Was that break intended, or should the new code fall back to the previous behavior if the stream being parsed can't provide an offset?